Turbofan mounting arrangement

Abstract

A gas turbine engine has a rear mounting structure incorporating a mounting apparatus attached to a bypass duct wall with a link device of six rods for transferring core portion related inertia-induced loads, from an inner case of the core portion in a short circuit across an annular bypass air passage to the bypass duct wall.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]The present invention is a continuation-in-part of co-pending application Ser. No. 12 / 466,426, filed on May 15, 2009.TECHNICAL FIELD[0002]The application relates generally to gas turbine engines and more particularly, to a turbofan engine mounting system.BACKGROUND OF THE ART[0003]A turbofan gas turbine engine basically includes a core portion which must be mounted inside a bypass duct. A traditional engine mount system for a fuselage mount turbofan gas turbine engine reacts to thrust, lateral and vertical loads at the front mounting plane (on the intermediate case of the engine), and reacts to lateral and vertical loads at the rear mount. The rear mount is usually located either on the bypass duct, forming a cantilever core as schematically shown in FIG. 9, or on the engine core, typically near the turbine exhaust case, forming a rear core mount as schematically shown in FIG. 10. However, the cantilever core suffers from distortion due t...

AI Technical Summary

Benefits of technology

[0006]In another aspect, the described subject matter provides a turbofan gas turbine engine comprising: a core portion including an inner case; an annular bypass duct wall surrounding and supporting the core portion, to thereby define a bypass air passage radially between the core portion and the bypass duct for directing a bypass air flow passing therethrough; and a rod frame structure including three pairs of first and second rods defined in a radial plane defined by the inner case, the rod frame structure interconnecting the bypass duct wall and the inner case for transferring core portion related inertia-induced loads from the inner case in a short circuit across the bypass air passage in the radial plane to the bypass duct wall, thereby reducing distortion of the core portion caused by the inertia-induced loads and reducing carcass bending of the core portion.

Problems solved by technology

However, the cantilever core suffers from distortion due to inertia loads and tends to droop from the burden of these loads, resulting in tip clearance loss which is critical to the functioning of an axial compressor.

The rear core mount suffers from significant bending of the core portion caused by thrust loads.

Increased carcass bending results in having to set larger initial tip clearances, which results in both loss of efficiency in the compressor and turbine, and is therefore critical for the operability of an all-axial compressor.

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